body,html{
    height:100%;
    padding: 0;
    margin: 0;
}
body{
	position: relative;
}
.main{
	width: 400px;
	height: 200px;
	background-color: #ccc;
	position: absolute;
	left: 50%;
	top: 50%;
	margin-left: -200px;
	margin-top: -100px;
}
.up,.down{
	width: 50px;
	height: 50px;
	background-color: #fc0;
}
.up{
	border-bottom-right-radius: 100%; 
}
.down{
	border-top-left-radius: 100%;
	position: relative;
	top: 100px;
	left: 350px;
}
